Who makes which essential components for life in an ecosystem without sunlight?
Finding out whether deep sea, hydrothermal vent communities can be self-sufficient in the total absence of sunlight is an important part of investigating the potential for life in the deep ocean of Europa. Carbon stable isotope analysis of individual lipid fatty acids from shrimp at two neighboring vent fields at the Mid-Cayman Rise allowed us to trace the origin of these essential components of all cells and discover which were provided in diet and which synthesized by the organism. We found that some essential fatty acids believed to be produced only by photosynthetic organisms had different carbon isotope compositions in fauna from the two sites, one shallower and one deeper than the other and therefore had been chemosynthesized locally in the absence of sunlight.
Streit K, Bennett SA, Van Dover CL and Coleman M (2015) Sources of organic carbon for Rimicaris hybisae: tracing individual fatty acids at two hydrothermal vent fields in the Mid-Cayman rise. Deep Sea Res. Part I 100 13–20. A PDF copy of the paper can be found here.